Sökning: "Northern boreal zone"

Visar resultat 1 - 5 av 18 avhandlingar innehållade orden Northern boreal zone.

  1. 1. Palaeoenvironmental changes in the northern boreal zone of Finland: local versus regional drivers

    Författare :Shyhrete Shala; Karin H. Helmens; Christian Bigler; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Palaeolimnology; Palaeoecology; Biological assemblages; Sediment geochemistry; Regional drivers; Local drivers; Quantitative temperature reconstructions; Transfer-functions; Holocene; MIS 5d-c; Northern boreal zone; NE Finland; kvartärgeologi; Quaternary Geology;

    Sammanfattning : Multiple proxies derived from the Lake Loitsana sediment sequence (NE Finland) are employed to determine the timing of deglaciation, characterise an early Holocene proglacial lake stage and reconstruct Holocene lake development. Local-scale processes causing shifts in biological assemblages are identified and the most likely Holocene mean July air temperature (Tjul) development is assessed. LÄS MER

  3. 2. Hydrogeochemical effects of hydropower regulation on river-aquifer continuum in boreal rivers

    Författare :Dmytro Siergieiev; Hjalmar Laudon; Luleå tekniska universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Geochemistry; hyporheic zone; hydrology; riparian zone; Element transport; Lule River; Kalix RIver; Northern Sweden; Earth sciences; Applied Geology; Tillämpad geologi;

    Sammanfattning : Hydropower infrastructure affects many large rivers worldwide, threatening riverine and coastal ecosystems by fragmenting flow, disturbing landscapes and water retention and altering sedimentation and primary production. This thesis investigated major impacts of hydropower regulation on hydrological and geochemical processes in large boreal rivers. LÄS MER

  4. 3. Microclimate at range margins : Consequences for boreal forest understory species

    Författare :Caroline Greiser; Kristoffer Hylander; Johan Ehrlén; Eric Meineri; Miska Luoto; Alistair Jump; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; microclimate; species distribution; range dynamics; boreal forest; canopy cover; topography; soil moisture; air humidity; bryophytes; lichens; vascular plants; biotic interactions; forest management; biodiversity conservation; ekologi och evolution; Ecology and Evolution;

    Sammanfattning : A warmer climate will shift species distributional range margins poleward, but near-ground microclimates may modify these shifts. Cold-adapted northern species at their rear edge may survive locally in microrefugia with a colder microclimate, and warm-adapted southern species at their leading edge may colonize stepping stone habitats with a warmer microclimate. LÄS MER

  5. 4. Boreal Lake Sediments as Sources and Sinks of Carbon

    Författare :Cristian Gudasz; Tranvik Lars; David Bastviken; Susan Ziegler; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; boreal lakes; allochthonous; lake sediments; sediment mineralization; bacterial production; bacterial biomass; carbon cycle; Freshwater ecology; Limnisk ekologi; Limnologi; Limnology;

    Sammanfattning : Inland waters process large amounts of organic carbon, contributing to CO2 and CH4 emissions, as well as storing organic carbon (OC) over geological timescales. Recently, it has been shown that the magnitude of these processes is of global significance. LÄS MER

  7. 5. Effects of climate change on boreal wetland and riparian vegetation

    Författare :Lotta Ström; Roland Jansson; Christer Nilsson; Sarah Gergel; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; biomass; flooding; hydrologic niche; invasibility; riparian zone; riparian plant species; river margin; climate scenario; seed sowing experiment; species composition; species richness; transplant experiment; Terrestrial ecology; Terrestrisk ekologi;

    Sammanfattning : Models of climate change predict that temperature will increase during the 21th century and the largest warming will take place at high northern latitudes. In addition to warming, predictions for northern Europe include increased annual precipitation and a higher proportion of the precipitation during winter falling as rain instead of snow. LÄS MER